1. Field of the Invention
This invention generally relates to a detachable plug-type connector for hydraulic systems, in particular for motor vehicles, for the connection of a pressure line to a hydraulic cylinder. The plug-type connector has a pin-shaped inner part which can be inserted into a boring of an outer part, whereby a seal is provided between the outer part and the inner part.
2. Background Information
Such a plug-type connector is disclosed, for example, in German Patent No. 44 04 731. The outer part is a part of a housing of the hydraulic cylinder. The seal is realized in the form of an O-ring which sits in a groove on the pin-shaped inner part or plug. The inner part is enlarged conically in its rear area. The guidance and the firm seating of the inner part in the stepped boring of the outer part are ensured by the enlarged outer surface and the front end, which has a smaller diameter. There is a support element between the seal and the conical enlargement of the inner part. A securing element which is realized in the form of a spring clip sits in slots which run diametrically opposite to one another in the outer part, and the spring clip serves to reduce the inside diameter of the boring. During installation, the inner part is introduced into the outer part and thus also into the spring clip. The spring clip is thereby expanded by the cone of the inner part. As the inner part is pushed further into the outer part, the spring clip arrives in the area of the securing element, which is formed by a significantly reduced outside diameter on the inner part (for example, a groove or a shoulder), and snaps in place as a result of the spring bias. It is then no longer possible to extract the inner part from the outer part.
For disassembly, the spring clip is pulled out of the slot, and the seal is removed from the plug-type connection along with the inner part. One disadvantage of this procedure is that when the plug-type connection is removed, the seal can become dirty or damaged, and when the seal is reinstalled at some later point it may no longer perform an ideal sealing action. It is also possible that the seal will be lost during this disassembly procedure. Significant disadvantages can also occur if, when the plug-type connection is detached, the seal comes into contact with petroleum products, for example, in particular if the hydraulic cylinder in question is a brake cylinder. Seals which are resistant to brake fluid are not resistant to petroleum and vice-versa. The gasket will consequently swell up and cease to perform its function. In the case cited by way of example, that would entail significant risks.
During assembly, the spring clip already sits in its securing position in the slots in the outer part, to clearly indicate to the mechanic by the locking of the inner part that the plug-type connection has been correctly made. If, as the inner part (the plug) is being introduced, the procedure is not performed extremely carefully, e.g. if the plug is introduced at an angle, the seal can be damaged when it comes into contact with the circlip or sealing ring, which can also have an undesirable affect on the operation of the hydraulic cylinder.